Secure Boot Validation at Shutdown for Automotive ECU

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Solution Overview

Problem

Standard sequential secure boot processes in automotive ECUs cause significant delays during startup, which can lead to loss of critical messages and safety functionality failures, as they require time-consuming validation of firmware integrity and authenticity.

Innovation Solution

Performing secure boot validation at shutdown and storing an authentication code in cache memory pre-authenticates the application, allowing bypass of authentication at subsequent boots, thereby reducing startup time by eliminating the need for sequential validation upon wake-up.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sequential secure boot validation is performed during startup, then firmware integrity and authenticity are verified, but startup time is significantly delayed

Engineering Contradiction:
Improvefirmware integrity verificationVSAvoidstartup delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs secure boot validation during the shutdown phase instead of during startup. The authentication code is generated and stored in cache memory before the system enters low-power mode. When the system wakes up, the pre-computed authentication code is already available, allowing the boot process to skip the time-consuming validation step and proceed directly to application execution, thus resolving the contradiction between verification reliability and startup speed

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an authentication code as an intermediary element. Instead of performing full secure boot validation during startup, the system uses a pre-computed authentication code stored in cache memory as a mediator to verify firmware integrity quickly. This intermediary allows the system to maintain security verification while dramatically reducing startup time

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If full secure boot validation is performed at each startup, then security is maintained, but communication with vehicle networks is delayed beyond the 100ms requirement

Engineering Contradiction:
Improvesecurity validationVSAvoidnetwork communication speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The patent moves the security validation process to occur during shutdown, completing the authentication code generation before the system enters low-power mode. This preliminary action ensures that when the system wakes up and needs to communicate with vehicle networks, the security verification has already been performed, allowing the ECU to meet the 100ms communication requirement while maintaining security

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent segments the secure boot process into two parts: authentication code generation during shutdown, and authentication code verification during startup. This segmentation allows the time-consuming validation work to be done when the system is shutting down, while the startup process only needs to perform a quick verification check, enabling timely network communication

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3923168B1Secure boot at shutdown
Publication Date: 2023.03.08 HARMAN INT IND INC
  • EP3923168B1 patent drawingFigure 1
  • EP3923168B1 patent drawingFigure 2

AI summary

A secure boot system and method to reduce a total time to boot by performing secure boot validation at shutdown and storing an authentication code in a secure manner, in effect, pre-authenticating an application so that, at the next boot, authentication may be bypassed..